1. Field of the Invention
The present invention relates to an ink jet printing apparatus and ink jet printing method, more particularly, it relates to an ink jet printing apparatus and ink jet printing method capable of printing at high speed and high image quality.
2. Description of the Related Art
Regarding an ink jet printing apparatus, technology is known that adjusts the distance (interval) between a print head and a platen for supporting a print medium (hereinafter referred to as print paper or media). For example, the interval between the print head and the platen (distance between the head and the paper) is adjusted in accordance with the thickness or type of the print medium, in the inventions disclosed in Japanese Patent Laid-Open Nos. 64-075248 (1989), 7-025109, 2002-292856, 2006-103278, 2004-042346, 2004-090461 and 2005-280206.
However, the above patent documents disclose no relationship between the number of scans (number of passes) of the print head and the distance between the head and the paper, although they do disclose a relationship between the type (thickness) of paper and the distance between the head and the paper. Additionally, as a result of diligent research for the relationship between the number of scans (number of passes) of the print head and the distance between the head and the paper, the inventors have newly found that it is effective to change the distance between the head and the paper in accordance with the number of passes.
That is, since the impact position deviation of ink is smaller as the distance between the head and the paper is shorter, it is desirable to reduce the distance between the head and the paper as much as possible. However, as the distance between the head and the paper is shorter, the print head easily comes into contact with the print paper. Thus, the distance between the head and the paper can be reduced only in the case where the print head hardly comes into contact with the print paper. In consideration of this, the relationship between the distance between the head and the paper and the number of passes was considered.
In a multi-pass mode for printing at a relatively large number of passes, the print head successively scans, many times, to a region where printing is performed by the preceding scan (preceding scan print region). In this case, even if a cockling occurs in the preceding scan print region, printing is not completed onto the whole region, and the succeeding scan is performed to the region where the cockling occurs. Then, there is a possibility that the head comes into contact with the cockling paper in the succeeding scan. Accordingly, it is difficult to reduce the distance between the head and the paper in the multi-pass mode.
On the other hand, in a limited-pass mode for printing at a relatively small number of passes, the print head does not scan again or scans, only a small number of times, the region where printing is performed by the preceding scan (preceding scan print region). In this case, printing is completed onto the preceding scan print region when the cockling occurs in the region, and there is a low possibility that the succeeding scan is performed to the region where the cockling occurs. Accordingly, there is a low possibility that the head comes into contact with the cockling paper in the succeeding scan, and the distance between the head and the paper can be reduced in the limited-pass mode.